A user equipment (UE) and a service base station operate power saving modes of individual connections based on service types, so that an amount of power consumption of the user equipment (UE) can be minimized. The term “Power Saving Class” is the power saving mode operation scheme defined by considering characteristics of individual traffics in the service types.
Each power saving class includes a sleep window and a listening window according to traffic characteristics based on the service types. For example, if a specific service connection generates irregular traffic data (e.g., Best Effort or non-real-time service traffic) and an irregular data transfer rate, the specific service connection is coupled to the power saving class composed of a constant listening window and an exponentially-increasing sleep window, which is then operated. On the other hand, another service connection (e.g., a real-time service or a Voice over IP (VoIP)) is coupled to another power saving class composed of a constant listening window and a constant sleep window.
In the case of the user equipment (UE) currently operated under the power saving mode defined in each power saving class, an activated power saving class may be deactivated by traffic generated in a corresponding connection, the user equipment (UE) sets an initial sleep window to a start sleep window in order to re-activate the corresponding power Saving class after completing traffic transmission.
Provided that the user equipment (UE) is operated under the power saving mode of the power saving class defined by consideration of individual traffic characteristics, if the activated class is terminated by the necessity of transmission of data irrelevant to the corresponding traffic and then restarts its operation, the advantages of using the individual power saving classes are useless, resulting in the occurrence of system inefficiency.
For example, in the case of non-real-time traffic data, if the traffic occurs once, the probability of successively generating the same service traffic is very high. If the traffic does not occur for at least a predetermined period of time, the probability of generating the corresponding traffic is gradually decreased as time goes by.
If the user equipment (UE) must deactivate the power saving class to transmit traffic data distinguished from the corresponding traffic when it is currently operated under the power saving mode based on the power saving class defined by consideration of the above-mentioned characteristics, the user equipment (UE) must be re-operated under the power saving mode of the initial sleep window although the occurrence of the corresponding traffic is not maintained for a long period of time.
And, the user equipment (UE) requires a long period of time until reaching the sleep window before the power saving class is deactivated. Transmission connections are connected to the same power saving class although they have different characteristics to transmit data distinguished from provided service traffic, and the power saving class must be deactivated and be then re-activated to transmit data distinguished from the above-mentioned traffic, the sleep window from the initial sleep window must be increased, resulting in reduction of the power saving effect.